1. Field of the Invention
The invention is the field of devices for transmitting force and relates to a conveyor unit and a conveyor system according to the generic term of the corresponding independent claims.
2. State of the Art
Such a conveyor unit is known, e.g. from CH 538 065 (U.S. Pat. No. 3,757,514). A link chain comprises links connected in ball and socket joint-manner, each one with a joint body and a joint socket. In order for a joint body to be able to be introduced into the joint socket of the following link, the joint socket is slotted and thus expandable. In order to prevent an expanding of the socket joint, a sleeve may be laid over it. The sleeve may also serve for low friction bearing of the chain link in a guidance.
In DE 31 21 835 A1 (or GB 2 077 811), a ball and socket link chain is described, the individual chain links of which are separated into two halves along an axial plane and after connection with a succeeding chain link are each held together by holding rings.
CH 655 916 (EP 0 091 557) describes a device for establishing a connection between stations of an installation. The device comprises a link chain similar to the one described in DE 31 21 835 A1, which, however, comprises through hole openings along the longitudinal axis of the chain links. Through these through holes an electric cable is laid, which serves the communication between two stations along the link chain. Instead of the electric cable a light conductor or a wave guide is mentioned. The link chain is conveyable out of a magazine by a first end of the chain. In the magazine, the chain lies in an unordered manner. On this first end of the link, the cable is made fast to a main station. At the other end of the link chain, or the cable, a coupling organ is arranged, which is connectable to the respective intermediate stations, which are arranged along a guiding channel. For this purpose the link chain is conveyed into a position, in which the coupling organ is located at the intermediate station. In this manner the cable can be connected to the intermediate station. There may also be several coupling organs, which are arranged at a distance along the link chain.
WO 98/13281 A1 discloses a force transmission means for transmission of pushing forces. It consists of a succession of transmission elements which abut on their faces and comprise a ring-like ridge or a ring-like groove, respectively, which are pivotable against each other. The transmission elements may comprise an axial through hole through which a connecting means for loose connection of the transmission elements, especially an electric cable is laid.
DE 102 40 487 A1 shows a chain of chain links and connection links arranged inside the chain. The connection links comprise a section in the shape of a calotte which cooperates with a ball-shaped bearing surface of the adjacent chain link. In a different embodiment adjacent chain links together form a ball and socket joint and the chain is held together by a steel cable running lengthwise and coaxially in relation to the chain. The cable may be pre-tensed.